Hubble Glimpses Merging Galaxy Clusters

The Hubble Space Telescope captured an image of a galaxy cluster known as CL0016+1609, or MACS J0018.5+1626. It is very bright at X-ray wavelengths and among the most extensively studied clusters at X-ray and radio wavelengths. X-ray observations revealed that it is actually two clusters merging along our line of sight.

Researchers observed CL0016+1609 with Hubble’s Advanced Camera for Surveys to measure the cluster's dark-matter distribution, information that helps study the merger and the cluster's role in the universe’s large-scale structure. Hubble cannot see dark matter directly, but its infrared and visible-light data reveal dark matter’s presence through gravitational lensing of normal matter.

The image also includes Wide Field Camera 3 data from a program that obtained the first Hubble infrared images of 46 massive galaxy clusters and searched for distant galaxies magnified by them. Called RELICS (Reionization Lensing Cluster Survey), the program found some 300 high-redshift candidate galaxies lensed by these clusters.

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